One type of 3D measuring device is a triangulation scanner that uses a triangulation method to measure the 3D coordinates of points on an object. The triangulation scanner usually includes a projector that projects onto a surface of the object either a pattern of light in a line or a pattern of light covering an area. A camera is coupled to the projector in a fixed relationship, for example, by attaching a camera and the projector to a common frame. The light emitted from the projector is reflected off the object surface and is detected by the camera. Since the camera and projector are arranged in a fixed relationship, the distance to the object may be determined using trigonometric principles. Compared to coordinate measurement devices that use tactile probes, triangulation systems provide advantages in quickly acquiring coordinate data over a large area. As used herein, the resulting collection of 3D coordinate values or data points of the object being measured by the triangulation system is referred to as point cloud data or simply a point cloud.
A situation commonly encountered by triangulation scanners used outdoors is saturation of camera arrays by bright sunlight. Another difficulty encountered by triangulation scanners the ability to acquire dense detail from 2D camera images while still retaining relatively high 3D accuracy using triangulation methods. Another difficulty of triangulation scanners is obtaining high-dynamic-range 3D images and colored 3D images based on two-dimensional (2D) color images having high dynamic range. Another difficulty of triangulation scanners is removing ambiguities in determining 3D coordinates A further difficulty is in determining color reflectance characteristics of objects being measured in three dimensions.
Accordingly, while existing 3D triangulation scanners are suitable for their intended purpose, the need for improvement remains, particularly in providing a 3D triangulation scanner with the features described here.